Members of the Childhood Cancer Research Core have conducted, or collaborated on numerous studies that have addressed questions relating to home or parental occupational exposures. The exposures of interest are wide-ranging, but have included pesticides, polynuclear aromatic hydrocarbons (PAHs), metals, radon, electromagnetic fields (EMF), environmental tobacco smoke (ETS), infectious agents, N-nitroso compounds, and solvents. The mainstay of these studies continues to be data collection through self-administered questionnaires or (more commonly) interviews of the parents of children with specific cancers and a matched control group. This approach is cost-effective. However, the Core members recognize the potential of the new molecular techniques to provide insights into the processes of tumorogenesis and/or to quantitate in-vivo exposure to environmental insult, and the need to do so on a cost-effective basis in large epidemiological studies. The Core is just starting a case-control study of non-Hodgkin?s lymphoma in children that will assess pesticide exposure and will measure the frequency of two specific chromosomal rearrangements mediated by the VDJ recombinase enzyme system.